Autonomous tracking based on radius

ABSTRACT

Disclosed is a configuration of an autonomous vehicle for autonomously following a moving subject based on a radius of a virtual sphere surrounding the autonomous vehicle. The autonomous vehicle may be an unmanned ground vehicle or an unmanned aerial vehicle, which autonomously follows the subject (e.g., a device, a live entity, or any object) based on the virtual sphere. The radius of the virtual sphere may be dynamically configured according to a velocity of the autonomous vehicle or configurations of a camera coupled to the autonomous vehicle. Accordingly, the autonomous vehicle can follow the subject along a smooth trajectory, and capture images of abrupt movements of the subject in a cinematically pleasing manner.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.15/445,464, filed on Feb. 28, 2017, the contents of which areincorporated by reference herein in their entirety.

TECHNICAL FIELD

The disclosure generally relates to a system and a method ofautonomously tracking a subject.

BACKGROUND

The proliferation of remote controlled vehicles and developments inimage processing introduce new approaches in recording of images. Forexample, a remote controlled vehicle (e.g., ground vehicle or aerialvehicle) controlled by a user can follow a moving subject (e.g., adevice, a live entity, or any object), while a camera mounted on orintegrated with the remote controlled vehicle captures images of themoving subject. The use of the remote controlled vehicle allows an imageof the moving object to be captured with a perspective view differentfrom a perspective view of the user. However, relying on the usercontrol to follow the moving subject is cumbersome, and is susceptibleto losing track of the subject that suddenly may move in an unexpecteddirection.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed embodiments have advantages and features which will bemore readily apparent from the detailed description, the appendedclaims, and the accompanying figures (or drawings). A brief introductionof the figures is below.

FIG. 1 illustrates an example configuration of a remote controlledaerial vehicle in communication with a remote controller, according toone or more embodiments.

FIG. 2 shows a perspective view of a remote controlled aerial vehicle,according to one or more embodiments.

FIG. 3 illustrates a block diagram of an example of a remote controlledaerial vehicle electronics and control system, according to one or moreembodiments.

FIG. 4 illustrates an example block diagram of a flight controller ofthe remote controlled aerial vehicle electronics and control system,according to one or more embodiments.

FIG. 5 illustrates a state transition diagram of a target positiongenerator of the flight controller, according to one or moreembodiments.

FIGS. 6A and 6B illustrate example arrangements of a previous targetposition and a virtual sphere.

FIG. 7 illustrates a flow diagram for autonomously determining a futuredestination of an aerial vehicle to track a subject based on a dynamicradius, according to one or more embodiments.

FIG. 8 illustrates example trajectories of a subject and the aerialvehicle following the subject based on a dynamic radius, according toone or more embodiments.

FIG. 9 illustrates an example computing machine.

DETAILED DESCRIPTION

The Figures (FIGS.) and the following description relate to preferredembodiments by way of illustration only. It should be noted that fromthe following discussion, alternative embodiments of the structures andmethods disclosed herein will be readily recognized as viablealternatives that may be employed without departing from the principlesof what is claimed.

Reference will now be made in detail to several embodiments, examples ofwhich are illustrated in the accompanying figures. It is noted thatwherever practicable similar or like reference numbers may be used inthe figures and may indicate similar or like functionality. The figuresdepict embodiments of the disclosed system (or method) for purposes ofillustration only. One skilled in the art will readily recognize fromthe following description that alternative embodiments of the structuresand methods illustrated herein may be employed without departing fromthe principles described herein.

Configuration Overview

Disclosed by way of example embodiments is an autonomous vehicle, onwhich a camera can be mounted, for autonomously following a movingsubject based on a radius of a virtual sphere surrounding the autonomousvehicle. The autonomous vehicle may be an unmanned ground vehicle or anunmanned aerial vehicle, which autonomously follows the subject (e.g., adevice, a live entity, or any object) based on the virtual sphere andcaptures an image of the moving subject. For ease of discussion,reference herein will be made to unmanned area vehicles, although theprinciples may apply to unmanned ground and/or water vehicles.

In one or more example embodiments, a flight plan including waypoints ortarget positions of the autonomous vehicle may be dynamically changedbased on (i) a previous target position of the autonomous vehicle withrespect to a position of the autonomous vehicle and (ii) a radius of thevirtual sphere. The previous target position may be a previouslydetermined waypoint or a previously determined target position of theautonomous vehicle. In one aspect, responsive to determining that theprevious target position is located outside of the virtual sphere, theprevious target position may be determined to be an updated targetposition of the autonomous vehicle (i.e., maintains the previous targetposition). Responsive to determining that the previous target positionis located within the virtual sphere, an intersection between (i) theprevious target position and a position of the subject and (ii) asurface of the virtual sphere may be determined to be the updated targetposition of the autonomous vehicle.

In one aspect, a virtual sphere may be dynamically configured. Theautonomous vehicle may be located on a center of the virtual sphere. Inone aspect, a radius of the virtual sphere may vary based on a velocityof the vehicle, configurations of the camera, or both. Exampleconfigurations of the camera include an orientation (e.g., pitch andheading), field of view, a frame rate, resolution, sensitivity to lightaccording to International Standards Organization (ISO), white balance,aperture, exposure, etc. For example, the radius is increased as thevelocity of the vehicle increases, or the radius may be decreased as thevelocity of the vehicle decreases. For another example, the radius maybe increased as a frame rate of the camera increases, and the radius isdecreased as the frame rate decreases.

Advantageously, dynamically configuring the virtual sphere surroundingthe autonomous vehicle and determining the updated target position ofthe autonomous vehicle according to the virtual sphere allow theautonomous vehicle to autonomously follow the subject moving in anunanticipated direction. Accordingly, the autonomous vehicle can followthe subject along a smooth trajectory, and capture images of abruptmovements of the subject in a cinematically pleasing manner.

Example Aerial Vehicle Configuration

FIG. 1 illustrates an example embodiment in which an aerial vehicle 110is a quadcopter (i.e., a helicopter with four rotors). The aerialvehicle 110 in this example includes a housing 130 for payload (e.g.,electronics, storage media, and/or camera), four arms 135, four rotors140, and four propellers 145. Each arm 135 may mechanically couple witha rotor 140 to create a rotary assembly. When the rotary assembly isoperational, all the propellers 145 may spin at appropriate speeds toallow the aerial vehicle 110 lift (take off), land, hover, move, androtate in flight. Modulation of the power supplied to each of the rotors140 may control the acceleration and torque on the aerial vehicle 110.

A gimbal 175 may be coupled to the housing 130 of the aerial vehicle 110through a removable coupling mechanism that mates with a reciprocalmechanism on the aerial vehicle 110. The coupling between the gimbal 175and the aerial vehicle 110 may have mechanical and communicativecapabilities. In some embodiments, the gimbal 175 may be attached orremoved from the aerial vehicle 110 without the use of tools. A camera115 may be mechanically coupled to the gimbal 175, so that the gimbal175 steadies and controls the orientation of the camera 115. It is notedthat in alternate embodiments, the camera 115 and the gimbal 175 may bean integrated configuration.

The aerial vehicle 110 may communicate with a device via a wirelessnetwork 125. The device that communicates with the aerial vehicle 110 isdescribed herein as being a remote controller 120. However, in alternateembodiments, the device may be any other computing device capable ofwireless communicating (e.g., transmitting, receiving, or both) with theaerial vehicle 110. Some or all of the description attributed herein tothe remote controller 120 may also be applied to other computing devicescapable of wireless communication. Other computing devices may include adevice with a screen that is used to display images or video captured bythe aerial vehicle but not to control the aerial vehicle, such as, alaptop, smartphone, tablet, or head-mounted display.

In one embodiment, the wireless network 125 may be a long range Wi-Fisystem. It also may include or be another wireless communication system,for example, one based on long term evolution (LTE), 3G, 4G, or 5Gmobile communication standards. In some embodiments, the wirelessnetwork 125 may be a single channel and the aerial vehicle 110 and theremote controller 120 implement a half-duplex system. In an alternateembodiment, the wireless network 125 includes two channels: aunidirectional channel used for communication of control informationfrom the remote controller 120 to the aerial vehicle 110 and a separateunidirectional channel used for video downlink from the aerial vehicle110 to the remote controller 120 (or to another device, such as a videoreceiver where direct video connection may be desired). Alternatewireless network configurations may also be used.

The remote controller 120 in this example includes a first control panel150, a second control panel 155, an ignition button 160, an auto-flightcontrol button 165, and a screen (or display) 170. One primary purposeof the remote controller 120 is to facilitate movement of the aerialvehicle 110. To facilitate such movement, the remote controller 120directs movement of a set point of the aerial vehicle 110. The set pointof the aerial vehicle 110 is a mobile point in space that the aerialvehicle 110 attempts to reach through movement. The location, speed, andtrajectory of the set point can be changed via instructions from aflight controller 315. When the aerial vehicle 110 reaches the setpoint, it hovers at that point until the location of the set point ischanged via instructions from the flight controller 315. Following thechange in location of the set point, the aerial vehicle 110 again movestowards the updated location of the set point. Thus movement of the setpoint of the aerial vehicle 110 informs movement of the aerial vehicle110 itself. Specifically, movement of the set point of the aerialvehicle 110 designates the speed, direction, and trajectory of theaerial vehicle 110.

As previously mentioned, the set point of the aerial vehicle 110 ischanged via input to the remote controller 120. The first control panel150 of remote controller 120 may be used to control “up-down” direction(e.g. lift and landing) of the set point of the aerial vehicle 110. Thesecond control panel 155 may be used to control “forward-reverse” or maycontrol the direction of the set point of the aerial vehicle 110. Inalternate embodiments, the control panels 150, 155 are mapped todifferent directions for the aerial vehicle 110. Each control panel 150,155 may be structurally configured as a joystick controller and/or touchpad controller. The ignition button 160 may be used to start the rotaryassembly (e.g., start the propellers 145). The auto-flight controlbutton 165 may be used to override the controls of the remote controller120 and transmit instructions to the aerial vehicle 110 to autonomouslytravel to a predefined location. The ignition button 160 and theauto-flight control button 165 may be mechanical and/or solid statepress sensitive buttons.

In addition, each button may be illuminated with one or more lightemitting diodes (LEDs) to provide additional details. For example a LEDmay switch from one visual state to another to indicate with respect tothe ignition button 160 whether the aerial vehicle 110 is ready to fly(e.g., lit green) or not (e.g., lit red) or whether the aerial vehicle110 is now in an auto-flight mode (e.g., lit yellow) or a manual flightmode (e.g., lit red). It also is noted that the remote controller 120may include other dedicated hardware buttons and switches and thosebuttons and switches may be solid state buttons and switches. Forexample, a button or switch may be configured to allow for triggering asignal to the aerial vehicle 110 to immediately execute a landingoperation.

The remote controller 120 may also include hardware buttons or othercontrols that control the gimbal 175 or camera 115. The remotecontroller 120 may allow it's user to change the preferred orientationof the camera 115. In some embodiments, the preferred orientation of thecamera 115 may be set relative to the angle of the aerial vehicle 110.In another embodiment, the preferred orientation of the camera 115 maybe set relative to the ground. The remote controller 120 may alsotransmit commands to the aerial vehicle 110 which are routed to thecamera 115 through the gimbal 175 to take a picture, record a video,change a picture or video setting, and the like.

The remote controller 120 also may include a screen 170 which providesfor visual display. The screen 170 may be a touch sensitive screen. Thescreen 170 also may be, for example, a liquid crystal display (LCD), anLED display, an organic LED (OLED) display, or a plasma screen. Thescreen 170 may allow for display of information related to the remotecontroller 120, such as menus for configuring the remote controller 120or remotely configuring the aerial vehicle 110. The screen 170 also maydisplay images or video captured from the camera 115 coupled with theaerial vehicle 110, wherein the images and video are transmitted to theremote controller 120 via the wireless network 125. The video contentdisplayed on the screen 170 may be a live feed of the video or a portionof the video captured by the camera 115. It is noted that the videocontent may be displayed on the screen 170 within a short time (e.g.,within fractions of a second) of being captured by the camera 115. Thedelay between the video being captured by the camera 115 and beingdisplayed on the screen 170 may be instantaneous or nearly instantaneousin terms of human perceptual quality.

The remote controller 120 shown in FIG. 1 is a dedicated remotecontroller, but in alternate embodiments the remote controller may beanother computing device such as a laptop, smartphone, or tablet that isconfigured to wirelessly communicate directly through an antenna systemwith the aerial vehicle 110 to control the aerial vehicle 110.

FIG. 2 illustrates an example of an aerial vehicle 110. The aerialvehicle 110 may be coupled to a camera 115 via a gimbal 175. The camera115 may capture video and send the video to the aerial vehicle 110through a bus of the gimbal 175. The aerial vehicle 110 may wirelesslytransmit the video to the remote controller 120. The aerial vehicle 110may include one or more internal antennas in the housing 130 fortransmitting signals to and receiving signals from the remote controller120. The one or more antennas may be omnidirectional. In someembodiments, the antennas of the aerial vehicle 110 radiate the majorityof their power beneath the aerial vehicle 110 (e.g., in the semi-spherebeneath the aerial vehicle 110).

FIG. 3 illustrates an example embodiment of electronics and control (EC)system 310 of the aerial vehicle 110. The EC system 310 may include aflight controller 315, an electronic speed controller 320, one or morethrust motors 240, a gimbal controller 330, a telemetric subsystem 335,a power subsystem 340, a video link controller 345, a camera interface350, and a long range communication subsystem 360. Each of thesecomponents is implemented as hardware, software, firmware, or anycombination thereof. The components communicate directly or indirectlywith each other through a data bus on the aerial vehicle 110.

In one embodiment, the communication subsystem 360 can be a long rangeWiFi system. It also can include or be another wireless communicationsystem, for example, one based on long term evolution (LTE), 3G, 4G, or5G mobile communication standards. The communication subsystem 360 alsocould be configured with a uni-directional RC channel for communicationof controls from the remote controller 120 to the aerial vehicle 110 anda separate unidirectional channel for video downlink from the aerialvehicle 110 to the remote controller 120 (or to a video receiver wheredirect video connection may be desired). The telemetric (or sensor)subsystem 335 may include navigational components, for example, agyroscope, accelerometer, a compass, a global positioning system (GPS)and/or a barometric sensor. The power subsystem 340 can include abattery pack and a protection circuit module as well as a powercontrol/battery management system. The camera interface 350 caninterface with a camera or may include an integrated camera. Theintegrated camera may be positioned similar to the camera mount 220 andthe camera may incorporate a camera mount.

The flight controller 315 of the EC system 310 may communicate with theremote controller 120 through the communication subsystem 360. Theflight controller 315 may control the flight related operations of theaerial vehicle 110 by control over the other components such as theelectronic speed controller 320 and the telemetric subsystem 335. Theflight controller 315 may interface with the gimbal controller 330 tocontrol the gimbal 175 and the video link controller 345 for cameraoperation control.

The electronic speed controller 320 may be configured to interface withthe thrust motors 240 to control the speed and thrust applied to therotors 140 via the thrust motors 240 (via electronics interface) of theaerial vehicle 110. The video link controller 345 may be configured tocommunicate with the camera interface 350 to capture and transmit imagesfrom a camera to the remote controller 120 (or other device with screensuch as a smart phone), e.g., via the communication subsystem 360. Thevideo may be overlaid and/or augmented with other data from the aerialvehicle 110 such as the telemetric (or sensor) data from the telemetricsubsystem 335. The power subsystem 340 is configured to manage andsupply power to the components of the EC system 310.

Example Autonomous Radius Tracking

FIG. 4 illustrates an example block diagram of a flight controller 315,according to one or more example embodiments. In one example embodiment,the flight controller 315 may include an input interface module 410, aradius tracking controller 420, a vehicle control interface module 450,and a gimbal control interface module 480. These components may operatetogether to autonomously control a movement of the aerial vehicle 110and change configurations of a camera based on a virtual sphere aroundthe aerial vehicle. These components may be embodied as hardware,software, firmware, or any combination thereof.

The input interface module 410 obtains information used forautomatically determining a flight plan including target positions ofthe aerial vehicle 110. In one example embodiment, the input interfacemodule 410 is communicatively coupled to the communication subsystem360, the telemetric subsystem 335, and the camera interface 350 of FIG.3. From the telemetric subsystem 335, the input interface module 410obtains vehicle position data F_data describing x, y, z coordinates of ameasured position F of the aerial vehicle 110, and a velocity dataF_v_data describing a velocity F_v of the aerial vehicle 110. Themeasured position F of the aerial vehicle 110 may be a current positionof the aerial vehicle 110 and the velocity F_V may be a current velocityof the aerial vehicle 110 measured by the telemetric subsystem 335. Fromthe communication subsystem 360, the input interface module 410 obtainssubject position data S_data describing x, y, z coordinates of a subjectposition S, based on a wireless signal describing the position of thesubject. Such wireless signal may be transmitted by the subject or byanother system monitoring the subject. Alternatively, the inputinterface module 410 may be coupled to a subject position estimationsubsystem (not shown) that estimates the subject position S. The subjectposition estimation subsystem analyzes a combination of an image of thesubject captured by the camera and time of light (e.g., infrared)measured by a ranging sensor attached to the aerial vehicle 110 andestimates the subject position with respect to the aerial vehicle 110 inthree dimensional space. Moreover, the subject position estimationsubsystem generates the subject position data S_data based on theestimated position of the subject. From the camera interface 350, theinput interface module 410 receives camera configuration data I_datadescribing current camera configurations I (e.g., pitch, heading, fieldof view, frame rate, resolution, sensitivity to light according to ISO,white balance, aperture, exposure, etc.). The input interface module 410provides the velocity data F_v_data, the position data F_data, thesubject position data S_data, the camera configuration data I_data tothe radius tracking controller 420.

The radius tracking controller 420 may receive data (e.g., F_v_data,F_data, S_data, I_data) from the input interface module 410 and maydetermine an updated target position W of the aerial vehicle 110 andupdated configurations C of the camera. In one embodiment, the radiustracking controller 420 may generate a virtual sphere, in which theaerial vehicle 110 is located on a center of the virtual sphere,according to the input data from the interface module 410. In addition,the radius tracking controller 420 may generate an updated targetposition data W_data describing the updated target position W of theaerial vehicle 110 and updated camera configuration data C_datadescribing updated configurations C of the camera, according to thevirtual sphere. Detailed description of the radius tracking controller420 is provided below with respect to FIGS. 5 through 8.

The vehicle control interface module 450 may receive the updated targetposition data W_data from the radius tracking controller 420. Thevehicle control interface module 450 may configure the electronic speedcontroller 320 and the thrust motors 240 to move the aerial vehicle 110towards the updated target position W as indicated by the updated targetposition data W_data. The vehicle control interface module 450 maydetermine a direction and a speed (or acceleration) of the aerialvehicle 110 to travel towards the updated target position W based on theupdated target position data W_data, and configure the electronic speedcontroller 320 and the thrust motors 240 according to the determineddirection and the speed (or acceleration) of the aerial vehicle 110.Hence, the aerial vehicle 110 travels towards the updated targetposition W.

The gimbal control interface module 480 may receive the updated cameraconfiguration data C_data from the radius tracking controller 420, andconfigures the gimbal controller 330 accordingly. In one aspect, theupdated camera configuration data C_data describes a desired pitch andheading of the camera. The gimbal control interface module 480 maydetermine a corresponding orientation of the gimbal 175, and mayconfigure the gimbal 175 according to the corresponding orientation suchthat the camera faces in the pitch and heading as indicated by theupdated camera configuration data C_data.

In one example embodiment, the radius tracking controller 420 mayinclude a radius generator 425, a target position generator 435, and acamera configuration controller 445. These components may operatetogether to dynamically generate a virtual sphere around the aerialvehicle 110, and generate the updated target position data W_data andthe updated camera configuration data C_data, according to the virtualsphere. These components of the radius tracking controller 420 may beembodied as hardware, software, firmware, or any combination thereof.

The radius generator 425 dynamically generates a virtual spheresurrounding the aerial vehicle 110. The aerial vehicle 110 is located ona center of the virtual sphere with a radius r. The radius r may bedynamically determined based on the velocity data F_v and the cameraconfiguration data I_data, as described in the following equation:

$\begin{matrix}{r = {r_{\min} + {\left( {r_{\max} - r_{\min}} \right)\frac{F\_ v}{{F\_ v}_{\max}}{f(I)}}}} & {{Eq}.\mspace{14mu}(1)}\end{matrix}$where r_(min) is a minimum radius of the virtual sphere; r_(max) is amaximum radius of the virtual sphere; F_v_(max) is a maximum velocity ofthe aerial vehicle; and f(I) is an adjustment factor based on the cameraparameters I. In one aspect, the radius r is proportional to thevelocity of the vehicle and a frame rate of the camera.

In one aspect, adjust factor f(I) is based on camera parameters I. Theadjustment factor f(I) outputs a normalized number between 0.0 and 1.0,according to camera parameters I. In one example, for a larger field ofview, a radius r becomes smaller to allow the aerial vehicle 110 to becloser to the subject while keeping the subject in frame. In oneexample, for a lower resolution, a lower frame rate, or both, the radiusr becomes smaller to allow the aerial vehicle 110 to be closer to thesubject. For low light, longer exposure, and/or higher sensitivity oflight (e.g., high ISO), the radius r becomes larger to smooth out themovement of the aerial vehicle 110. According to the adjustment factorf(I), capture image of the subject can be optimized in a cinematicallypleasing manner at a cost of degraded tracking performance. In oneexample, the adjustment factor f(I) can be obtained according to thefollowing equation:

$\begin{matrix}{{F(I)} = {{{FSF}\left( \frac{I_{FOV}}{{FOV}_{MAX} - {FOV}_{MIN}} \right)} + {{ISF}\left( \frac{I_{ISO}}{{ISO}_{MAX} - {ISO}_{MIN}} \right)}}} & {{Eq}.\mspace{14mu}(2)}\end{matrix}$where FSF is a scale factor for field of view (FOV); I_(FOV) is an inputFOV of the camera parameters I; FOV_(MAX) is a maximum FOV of thecamera; FOV_(MIN) is a minimum FOV of the camera; ISF is a scale factorfor sensitivity of light in ISO; I_(ISO) is an input ISO of the cameraparameters I; ISO_(MAX) is a maximum ISO of the camera; ISO_(MIN) is aminimum ISO of the camera.

The target position generator 435 may determine an updated targetposition W of the aerial vehicle 110 based on the radius r determined bythe radius generator 425. In one aspect, the target position generator435 operates in at least two states according to previous targetposition W_L of the aerial vehicle 110 and the virtual sphere. Forexample, if the previous target position W_L is located outside of thevirtual sphere, the target position generator 435 operates in anout-state to determine the updated target position W of the aerialvehicle 110 based on the previous target position W_L. If the previoustarget position W_L is located within the virtual sphere, the targetposition generator 435 operates in an in-state to determine the updatedtarget position W of the aerial vehicle based on the virtual sphere, theprevious target position W_L and the subject position S. Additionaldescription of operations of the target position generator 435 indifferent states is provided below with respect to FIGS. 5-8.

The camera configuration controller 445 may determine configurations ofthe camera based on the updated target position data W_data and thesubject position data S_data. In one aspect, the camera configurationcontroller 445 determines an anticipated flight path of the subjectbased on the subject position S or a previous trajectory of the subject.Moreover, the camera configuration controller 445 may determine thepitch and heading of the camera according to a flight path of the aerialvehicle 110 towards the updated target position W and an anticipatedposition of the subject. In particular, the camera configurationcontroller may determine the pitch and heading of the camera to face thesubject while the aerial vehicle 110 travels towards the updated targetposition W. Accordingly, images of the moving subject can be captured,while the aerial vehicle 110 travels towards the updated target positionW.

Referring now to FIG. 5, it illustrates a state transition diagram ofthe target position generator 435, according to one or more exampleembodiments. The target position generator 435 may determine whether theprevious target position W_L is within the virtual sphere or outside ofthe virtual sphere, and operates in a state corresponding to thedetermination. In one aspect, the target position generator 435 obtainsa distance d between a measured position F (e.g., current position) ofthe aerial vehicle 110 and the previous target position W_L of theaerial vehicle 110 and compares the distance d with the radius r of thevirtual sphere to determine whether the previous target position W_L iswithin or outside of the virtual sphere. If the distance d is less thanthe radius r, the target position generator 435 may determine that theprevious target position W_L is within the virtual sphere and operatesin an in-state. If the distance d is larger than the radius r, thetarget position generator 435 may determine that the previous targetposition W_L is outside of the virtual sphere and operates in anout-state.

FIGS. 6A and 6B illustrate example arrangements of a previous targetposition W_L and a virtual sphere. Specifically, FIG. 6A illustrates anexample arrangement of the previous target position W_L located withinthe virtual sphere, where the target position generator 435 operates inthe in-state. FIG. 6B illustrates an example arrangement of the previoustarget position W_L located outside of the virtual sphere, where thetarget position generator 435 operates in the out-state.

Turning back to FIG. 6A, the target position generator 435 may operatein the in-state. In the example in FIG. 6A, the distance d between theprevious target position W_L and the measured position F of the aerialvehicle 110 is less than the radius r of the virtual sphere. Hence, thetarget position generator 435 may determine that the previous targetposition W_L is within the virtual sphere, and operates in the in-state.In the in-state, the target position generator 435 may determine theupdated target position W to direct the aerial vehicle 110 towards thesubject along a smooth trajectory. For example, the target positiongenerator 435 determines the updated target position W to be anintersection W_I between (i) a direct path the previous target positionW_L and the subject position S and (ii) a surface of the virtual sphere.An example algorithm of identifying the intersection W_I is providedbelow in table 1.

Table 1 shows one example approach of identifying the intersection W_Iin the in-state.

Algorithm     /* distance in x y */     diff_x = W_x − W_Lx;     diff_y= W_y − W_Ly;     a = (diff_x * diff_x) + (diff_y * diff_y);     b2 =((−W_Lx * diff_x) + (−W_Ly * diff_y));     c = (W_Lx * W_Lx) + (W_Ly *W_Ly) − (r{circumflex over ( )}2);     pby2 = b2 / a;     q = c / a;    delta = pby2 * pby2 − q;     dsqr = sqrt(delta);     u1 = −pby2 +dsqr;     u2 = −pby2 − dsqr;     ix0 = W_Lx − diff_x * u1;     iy0 =wp_y0 − diff_y * u1;     ix1 = W_Lx − diff_x * u2;     iy1 = W_Ly −diff_y * u2;     if (W_Lx <= ix0 && ix0 <= W_x)     {     ix = ix0;    iy = iy0;     }     else     {     ix = ix1;     iy = iy1;     } //W_x is x-coordinate of S with respect to F. // W_y is y-coordinate of Swith respect to F. // W_Lx is x-coordinate of W_L with respect to F //W_Ly is y-coordinate of W_L with respect to F // ix is x-coordinate ofW_I with respect to F // iy is y-coordinate of W_I with respect to F

In one or more example embodiments, the target position generator 435may further determine the updated target position based on environmentalcondition data (e.g., wind speed and direction), terrain condition data(e.g., locations of tall dense shrubs), and other information necessaryfor planning a flight of the aerial vehicle.

Referring to FIG. 6B, the target position generator 435 may operate inthe out-state. In the example in FIG. 6B, the distance d between theprevious target position W_L and the measured position F of the aerialvehicle 110 is larger than the radius r of the virtual sphere. Hence,the target position generator 435 determines that the previous targetposition W_L is outside of the virtual sphere, and operates in theout-state. In the out-state, the target position generator 435 maydetermine the previous target position W_L to be the updated targetposition W (i.e., maintains the previous target position W_L), such thatthe aerial vehicle 110 continues to travel towards the previous targetposition W_L.

FIG. 7 illustrates a flow diagram for autonomously determining a futuredestination of the aerial vehicle 110 to track a subject based on adynamic radius, according to one or more embodiments. The steps in FIG.7 may be performed by, for example, the radius tracking controller 420of FIG. 4. In some example embodiments, some or all of the steps in FIG.7 may be performed by other entities (e.g., remote controller or othercomputing system). In addition, some example embodiments may perform thesteps in parallel, perform the steps in different orders, or performdifferent, fewer, or additional steps.

The radius tracking controller 420 may determine 710 the radius r of avirtual sphere, in which the aerial vehicle 110 is located on a centerof the virtual sphere. The radius r may be dynamically determined basedon the velocity F_v of the aerial vehicle, the camera configurations I(e.g., pitch, heading, frame rate, etc.) or a combination of them.

The radius tracking controller 420 may determine 720 a distance dbetween a measured position F of the aerial vehicle 110 and a previoustarget position W_L. The previous target position W_L is a previouslydetermined target position of the aerial vehicle 110 as part of a flightplan, and may be cached by the radius tracking controller 420. Becausethe aerial vehicle 110 is located on the center of the virtual sphere,the distance d between the measured position F of the aerial vehicle 110and the previous target position W_L is also a distance between thecenter of the virtual sphere and the previous target position W_L.

The radius tracking controller 420 compares 730 the distance d and theradius r to determine whether the previous target position W_L of theaerial vehicle 110 is within the virtual sphere or not. Moreover, theradius tracking controller 420 determines a state of operation fordetermining an updated target position W of the aerial vehicle 110 basedon the determination of the location of the previous target position W_Lwith respect to the virtual sphere.

Responsive to determining that the distance d is larger than the radiusr, the radius tracking controller 420 operates in the out-state. In theout-state, the radius tracking controller 420 sets 740 the previoustarget position W_L to be the updated target position W. Hence, theaerial vehicle 110 continues to travel towards the previous targetposition W_L.

Responsive to determining that the distance d is less than the radius r,the radius tracking controller 420 operates in the in-state. In thein-state, the radius tracking controller 420 determines 745 anintersection W_I between (i) a direct path between the previous targetposition W_L and the subject position S and (ii) a surface of thevirtual sphere. In addition, the radius tracking controller 420 sets 755the determined intersection W_I to be the updated target position W.

FIG. 8 illustrates example trajectories of a subject 810 and an aerialvehicle 110 following the subject based on a dynamic radius, accordingto one or more embodiments. The aerial vehicle 110 may be the aerialvehicle 110 of FIG. 1. In FIG. 8, the subject 810 (e.g., a person ridinga motorbike) making a sharp turn travels along a trajectory 830 to passpositions S1, S2 . . . S6 in that sequence. Meanwhile, the aerialvehicle 110 follows the subject 810 along a smooth trajectory 840 topass positions F1, F2 . . . F7 in that sequence. Because the aerialvehicle 110 continues to travel towards the previous target position W_Lin the out-state until the previous target position W_L is within thevirtual sphere in the in-state, a response of the aerial vehicle 110 toa quick movement of the subject 810 may be delayed. Such delay allowsthe aerial vehicle 110 to travel along the smoother trajectory 840 thanthe sharp trajectory 830, and captures images of abrupt movements of thesubject 810 in a cinematically pleasing manner.

Example Machine Architecture

As has been noted, the remote controlled aerial vehicle 110 can beremotely controlled from the remote controller 120. The aerial vehicle110 and the remote controller 120 are machines that may be configuredoperated using software. FIG. 9 is a block diagram illustratingcomponents of an example machine able to read instructions from amachine-readable medium and execute them in one or more processors (orcontrollers). All or portions of the example machine described in FIG. 9may be present and/or used with the aerial vehicle 110 and/or the remotecontroller 120 and/or other parts of a system that interfaces with theaerial vehicle 110 and/or remote controller 120.

In FIG. 9 there is a diagrammatic representation of a machine in theexample form of a computer system 900. The computer system 900 can beused to execute instructions 924 (e.g., program code or software) forcausing the machine to perform any one or more of the methodologies (orprocesses) described herein. In alternative embodiments, the machineoperates as a standalone device or a connected (e.g., networked) devicethat connects to other machines. In a networked deployment, the machinemay operate in the capacity of a server machine or a client machine in aserver-client network environment, or as a peer machine in apeer-to-peer (or distributed) network environment.

The machine in this example is a handheld controller to control theremote controlled aerial vehicle, e.g., 110. However, the architecturedescribed may be applicable to other computer systems that operate inthe system of the remote controlled aerial vehicle, e.g., 110, withcamera and mounting configuration, e.g., in setting up a localpositioning system. These other example computer systems include aserver computer, a client computer, a personal computer (PC), a tabletPC, a smartphone, an internet of things (IoT) appliance, a networkrouter, switch or bridge, or any machine capable of executinginstructions 924 (sequential or otherwise) that specify actions to betaken by that machine. Further, while only a single machine isillustrated, the term “machine” shall also be taken to include anycollection of machines that individually or jointly execute instructions924 to perform any one or more of the methodologies discussed herein.

The example computer system 900 includes one or more processing units(generally processor 902). The processor 902 is, for example, a centralprocessing unit (CPU), a graphics processing unit (GPU), a digitalsignal processor (DSP), a controller, a state machine, one or moreapplication specific integrated circuits (ASICs), one or moreradio-frequency integrated circuits (RFICs), or any combination ofthese. The computer system 900 also includes a main memory 904. Thecomputer system may include a storage unit 916. The processor 902,memory 904 and the storage unit 916 communicate via a bus 908.

The computer system 900 may include a static memory 906, a screen driver910 (e.g., to drive a screen, e.g., 170, such as plasma display panel(PDP), a liquid crystal display (LCD), or a projector). The computersystem 900 may also include input/output devices, e.g., an alphanumericinput device 912 (e.g., a keyboard), a dimensional (e.g., 2-D or 3-D)control device 914 (e.g., a mouse, a trackball, a joystick, a motionsensor, or other pointing instrument), a signal generation device 918(e.g., a speaker), and a network interface device 920, which also areconfigured to communicate via the bus 908.

The storage unit 916 includes a machine-readable medium 922 on which isstored instructions 924 (e.g., software) embodying any one or more ofthe methodologies or functions described herein. The instructions 924may also reside, completely or at least partially, within the mainmemory 904 or within the processor 902 (e.g., within a processor's cachememory) during execution thereof by the computer system 900, the mainmemory 904 and the processor 902 also constituting machine-readablemedia. The instructions 924 may be transmitted or received over anetwork 926 via the network interface device 920.

While machine-readable medium 922 is shown in an example embodiment tobe a single medium, the term “machine-readable medium” should be takento include a single medium or multiple media (e.g., a centralized ordistributed database, or associated caches and servers) able to storethe instructions 924. The term “machine-readable medium” shall also betaken to include any medium that is capable of storing instructions 924for execution by the machine and that cause the machine to perform anyone or more of the methodologies disclosed herein. The term“machine-readable medium” includes, but not be limited to, datarepositories in the form of solid-state memories, optical media, andmagnetic media.

Additional Considerations

The disclosed configuration beneficially allows an aerial vehicle, e.g.,110, to autonomously follow a moving subject based on a virtual spheresurrounding the aerial vehicle. By adjusting a target position of theaerial vehicle 110 based on the previous determined target position withrespect to the virtual sphere, the aerial vehicle 110 can respond tosudden or unanticipated movements of a subject by moving following asmooth trajectory. Moreover, the camera coupled to the aerial vehiclecan face the moving subject while traveling along the smooth path tocapture images of such abrupt movements of the subject.

The disclosed configurations also can be applied to other types ofaerial vehicles or unmanned ground vehicles.

Throughout this specification, plural instances may implementcomponents, operations, or structures described as a single instance.Although individual operations of one or more methods are illustratedand described as separate operations, one or more of the individualoperations may be performed concurrently, and nothing requires that theoperations be performed in the order illustrated. Structures andfunctionality presented as separate components in example configurationsmay be implemented as a combined structure or component. Similarly,structures and functionality presented as a single component may beimplemented as separate components. These and other variations,modifications, additions, and improvements fall within the scope of thesubject matter herein.

Certain embodiments are described herein as including logic or a numberof components, modules, or mechanisms, for example, as illustrated anddescribed within FIGS. 3-13. Modules may constitute either softwaremodules (e.g., code embodied on a machine-readable medium or in atransmission signal) or hardware modules. A hardware module is tangibleunit capable of performing certain operations and may be configured orarranged in a certain manner. In example embodiments, one or morecomputer systems (e.g., a standalone, client or server computer system)or one or more hardware modules of a computer system (e.g., a processoror a group of processors) may be configured by software (e.g., anapplication or application portion) as a hardware module that operatesto perform certain operations as described herein.

In various embodiments, a hardware module may be implementedmechanically or electronically. For example, a hardware module maycomprise dedicated circuitry or logic that is permanently configured(e.g., as a special-purpose processor, such as a field programmable gatearray (FPGA) or an application-specific integrated circuit (ASIC)) toperform certain operations. A hardware module may also compriseprogrammable logic or circuitry (e.g., as encompassed within ageneral-purpose processor or other programmable processor) that istemporarily configured by software to perform certain operations. Itwill be appreciated that the decision to implement a hardware modulemechanically, in dedicated and permanently configured circuitry, or intemporarily configured circuitry (e.g., configured by software) may bedriven by cost and time considerations.

The various operations of example methods described herein may beperformed, at least partially, by one or more processors, e.g.,processor 902, that are temporarily configured (e.g., by software) orpermanently configured to perform the relevant operations. Whethertemporarily or permanently configured, such processors may constituteprocessor-implemented modules that operate to perform one or moreoperations or functions. The modules referred to herein may, in someexample embodiments, comprise processor-implemented modules.

The one or more processors may also operate to support performance ofthe relevant operations in a “cloud computing” environment or as a“software as a service” (SaaS). For example, at least some of theoperations may be performed by a group of computers (as examples ofmachines including processors), these operations being accessible via anetwork (e.g., the Internet) and via one or more appropriate interfaces(e.g., application program interfaces (APIs).)

The performance of certain of the operations may be distributed amongthe one or more processors, not only residing within a single machine,but deployed across a number of machines. In some example embodiments,the one or more processors or processor-implemented modules may belocated in a single geographic location (e.g., within a homeenvironment, an office environment, or a server farm). In other exampleembodiments, the one or more processors or processor-implemented modulesmay be distributed across a number of geographic locations.

Some portions of this specification are presented in terms of algorithmsor symbolic representations of operations on data stored as bits orbinary digital signals within a machine memory (e.g., a computermemory). These algorithms or symbolic representations are examples oftechniques used by those of ordinary skill in the data processing artsto convey the substance of their work to others skilled in the art. Asused herein, an “algorithm” is a self-consistent sequence of operationsor similar processing leading to a desired result. In this context,algorithms and operations involve physical manipulation of physicalquantities. Typically, but not necessarily, such quantities may take theform of electrical, magnetic, or optical signals capable of beingstored, accessed, transferred, combined, compared, or otherwisemanipulated by a machine. It is convenient at times, principally forreasons of common usage, to refer to such signals using words such as“data,” “content,” “bits,” “values,” “elements,” “symbols,”“characters,” “terms,” “numbers,” “numerals,” or the like. These words,however, are merely convenient labels and are to be associated withappropriate physical quantities.

Unless specifically stated otherwise, discussions herein using wordssuch as “processing,” “computing,” “calculating,” “determining,”“presenting,” “displaying,” or the like may refer to actions orprocesses of a machine (e.g., a computer) that manipulates or transformsdata represented as physical (e.g., electronic, magnetic, or optical)quantities within one or more memories (e.g., volatile memory,non-volatile memory, or a combination thereof), registers, or othermachine components that receive, store, transmit, or displayinformation.

As used herein any reference to “one embodiment” or “an embodiment”means that a particular element, feature, structure, or characteristicdescribed in connection with the embodiment is included in at least oneembodiment. The appearances of the phrase “in one embodiment” in variousplaces in the specification are not necessarily all referring to thesame embodiment.

Some embodiments may be described using the expression “coupled” and“connected” along with their derivatives. For example, some embodimentsmay be described using the term “coupled” to indicate that two or moreelements are in direct physical or electrical contact. The term“coupled,” however, may also mean that two or more elements are not indirect contact with each other, but yet still co-operate or interactwith each other. The embodiments are not limited in this context.

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a process,method, article, or apparatus that comprises a list of elements is notnecessarily limited to only those elements but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus. Further, unless expressly stated to the contrary,“or” refers to an inclusive or and not to an exclusive or. For example,a condition A or B is satisfied by any one of the following: A is true(or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B are true (orpresent).

Use of the “a” or “an” may be employed to describe elements andcomponents of the embodiments herein. This is done merely forconvenience and to give a general sense of the invention. Thisdescription should be read to include one or at least one and thesingular also includes the plural unless it is obvious that it is meantotherwise.

Upon reading this disclosure, those of skill in the art will appreciatestill additional alternative structural and functional designs for asystem and a process for autonomously following a subject based on aradius of a virtual sphere through the disclosed principles herein.Thus, while particular embodiments and applications have beenillustrated and described, it is to be understood that the disclosedembodiments are not limited to the precise construction and componentsdisclosed herein. Various modifications, changes and variations, whichwill be apparent to those skilled in the art, may be made in thearrangement, operation and details of the method and apparatus disclosedherein without departing from the spirit and scope defined in theappended claims.

What is claimed is:
 1. A vehicle comprising: a camera; a radius trackingcontroller configured to: determine a radius of a virtual sphere aroundthe vehicle based on the camera, and determine an updated targetposition of the vehicle based on a comparison between a vehicle positionof the vehicle and a previous target position of the vehicle and basedon the radius; and a vehicle controller interface configured to move thevehicle towards the updated target position.
 2. The vehicle of claim 1,wherein the radius of the virtual sphere is determined based on aconfiguration of the camera and a velocity of the vehicle.
 3. Thevehicle of claim 2, wherein the configuration of the camera includes anyof orientation, field of view, frame rate, resolution, sensitivity tolight, white balance, aperture, and exposure.
 4. The vehicle of claim 1,wherein the radius tracking controller is further configured to: set theprevious target position to be the updated target position in responseto determining that a distance between the vehicle position and theprevious target position is larger than the radius.
 5. The vehicle ofclaim 1, wherein the radius tracking controller is further configuredto: determine an intersection between a path between the previous targetposition and a subject position of an image captured by the camera; anddetermine a surface of the virtual sphere around the vehicle in responseto determining that a distance between the vehicle position and theprevious target position of the vehicle is less than the radius.
 6. Thevehicle of claim 5, further comprising: a subject position estimationsubsystem configured to estimate the subject position and to provide theestimated subject position to the radius tracking controller.
 7. Thevehicle of claim 5, further comprising: a communication subsystemconfigured to receive information describing the subject position and toprovide the subject position to the radius tracking controller.
 8. Thevehicle of claim 1, further comprising: a telemetric subsystemconfigured to determine the vehicle position and to provide the vehicleposition to the radius tracking controller.
 9. The vehicle of claim 1,wherein the radius tracking controller is further configured to:determine a pitch and a heading of the camera to face an anticipatedposition of a subject of an image based on the updated target position,wherein the vehicle further comprises a gimbal controller securing thecamera, the gimbal controller configured to situate the camera accordingto the pitch and the heading.
 10. A method comprising: determining aradius of a virtual sphere around a vehicle based on a camera;determining an updated target position of the vehicle based on acomparison between a vehicle position of the vehicle and a previoustarget position of the vehicle and based on the radius; and moving thevehicle towards the updated target position.
 11. The method of claim 10,wherein the radius of the virtual sphere is determined based on aconfiguration of the camera and a velocity of the vehicle.
 12. Themethod of claim 11, wherein the configuration of the camera includes anyof orientation, field of view, frame rate, resolution, sensitivity tolight, white balance, aperture, and exposure.
 13. The method of claim10, further comprising: setting the previous target position to be theupdated target position in response to determining that a distancebetween the vehicle position and the previous target position is largerthan the radius.
 14. The method of claim 10, further comprising:determining an intersection between a path between the previous targetposition and a subject position of an image captured by the camera; anddetermining a surface of the virtual sphere around the vehicle inresponse to determining that a distance between the vehicle position andthe previous target position of the vehicle is less than the radius. 15.The method of claim 10, further comprising: determining a pitch and aheading of the camera to face an anticipated position of a subject of animage captured by the camera based on the updated target position; andsituating the camera based on the determined pitch and the heading. 16.An aerial vehicle comprising: a radius tracking controller configuredto: determine a radius of a virtual sphere around the aerial vehiclebased on a velocity of the vehicle, and determine an updated targetposition of the aerial vehicle based on the radius and a comparisonbetween a position of the aerial vehicle and a previous target positionof the aerial vehicle; and a vehicle controller interface moduleconfigured to move the aerial vehicle towards the updated targetposition of the aerial vehicle.
 17. The aerial vehicle of claim 16,further comprising: a gimbal configured to secure a camera, wherein theradius is determined further based on a configuration of the camera. 18.The aerial vehicle of claim 17, wherein the configuration of the cameraincludes any of orientation, field of view, frame rate, resolution,sensitivity to light, white balance, aperture, and exposure.
 19. Theaerial vehicle of claim 17, wherein the radius tracking controller isfurther configured to: determine an intersection between a path betweenthe previous target position and a subject position of an image capturedby the camera, and a surface of the virtual sphere around the aerialvehicle in response to a determination that a distance between theposition of the aerial vehicle and the previous target position is lessthan the radius.
 20. The aerial vehicle of claim 16, wherein the radiustracking controller is further configured to: set the previous targetposition to be the updated target position of the aerial vehicle inresponse to a determination that a distance between the position of theaerial vehicle and the previous target position is larger than theradius.